Field of the Invention
The present invention relates to a management system that detects spindle failure in a machine tool. In particular, it relates to a management device that manages a plurality of machine tools connected to a network, and detects spindle failure in the machine tool, and a non-transitory computer readable medium encoded with a computer program. In addition, it relates to a spindle failure detection method using the management device.
Related Art
Conventionally, if spindle failure of a machine tool occurs, the machining precision on a workpiece which is the machining target will decline, and there is a possibility of producing a defective workpiece. It should be noted that “spindle failure” refers to the matter of damage, wear, deformation of each part of the spindle, and entering a state in which each part of the spindle cannot exhibit the original function thereof, and for example, a case of a bearing of the spindle, etc. being damaged can be exemplified. Damage/wear/deformation of components pertaining (installed) to the spindle, and the matter of entering a state in which these components cannot exhibit the functions thereof, may be encompassed by “spindle failure”.
As one technique for avoiding a decline, etc. in machining precision of a workpiece caused by spindle failure in this way, it has been considered to adopt a device that detects spindle failure. For example, in a case of a bearing or the like of the spindle being damaged, it has been known that vibrations of a specific frequency will generate according to the balls (steel balls), etc. constituting the bearing in the thrust direction and radial direction of the spindle. Therefore, it has been considered to install an AE (Acoustic Emission) sensor or acceleration sensor to the spindle so as to configure a device that detects anomalies by analyzing these sensor outputs.
For a machine tool in the case of installing sensors to the spindle and using a device that analyzes the sensor output thereof in this way, a block diagram of the configuration for detecting anomalies is shown in. FIG. 4. First, as shown in FIG. 6, sensors 12a, 12b are installed to the spindle 10. Herein, the sensor 12a is an AE sensor, for example, and the sensor 12b may be established as an acceleration sensor. The output signals of these sensors 12a, 12b are amplified by an amplifier 14, and supplied to an analysis device 16. The analysis device 16 is a computer, for example, and in the case of analyzing the output signals of the sensors 12a, 12b and determining that an anomaly is occurring, externally outputs a failure detection signal. A program of the computer, which is the analysis device 16, executes analysis of the output signals of the sensors 12a, 12b by a predetermined algorithm, to determine whether or not an anomaly is occurring. In addition, the principle of such an analysis device 16, and a method of detecting spindle failure using a device such as the analysis device 16 are disclosed in Patent Document 1 noted below, for example.
On the other hand, a method of detecting failure of each part of a machine tool by detecting the load fluctuation from the electrical current value of a spindle motor or the like is disclosed in Patent Document 2 noted below. The method disclosed in this document has the object of mainly performing detection of load fluctuation, particularly damage of the tool based on the load fluctuation. This method described in Patent Document 2 records and detects load fluctuation, i.e. only load amount, and the fluctuation of specific frequencies are not recorded.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2005-74545
Patent Document 2: Japanese Examined Patent Application Publication No. S59-49145